Be very careful with where you insert the jumper. Some pins carry power, so shorting those would not be a good idea. Third row from the end.

Be very careful with where you insert the jumper. Some pins carry power, so shorting those would not be a good idea. Third row from the end.

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[[File:Jump-pins-5-6.jpg|left|thumb|500px|20 AWG wire used to connect P1 pins 5 and 6 to boot RPi into safe mode. Also, 20 AWG wire insulation used to protect the power pins on the P1 header from accidentally being shorted to another pin or each other. ]]

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More info:

More info:

http://www.raspberrypi.org/phpBB3/viewtopic.php?f=29&t=12007

http://www.raspberrypi.org/phpBB3/viewtopic.php?f=29&t=12007

Revision as of 18:22, 28 December 2012

This results in config.txt being ignored (except for avoid_safe_mode). A default cmdline.txt is applied, and kernel_emergency.img is loaded (if not available, then just kernel.img).

It provides a means of recovering from, e.g.

too high an overclock

a typo in cmdline.txt

an incorrect kernel=<filename> parameter

an invalid display mode

without requiring a PC.
(Obviously it won't help if you've deleted start.elf...)

The busybox based kernel_emergency.img has /boot mounted, and vi installed so you can fix up config.txt or cmdline.txt.
(You can also mount /dev/mmcblk0p2 and fix up the rootfs if you have problems there that stop you booting).

Short Jumpers 5&6.
Be very careful with where you insert the jumper. Some pins carry power, so shorting those would not be a good idea. Third row from the end.

20 AWG wire used to connect P1 pins 5 and 6 to boot RPi into safe mode. Also, 20 AWG wire insulation used to protect the power pins on the P1 header from accidentally being shorted to another pin or each other.